Cushing’s disease in dogs causes a cluster of symptoms including increased thirst and urination, increased appetite, a pot-bellied appearance.
You’re watching your dog drink more water than usual. She’s having accidents in the house, eating like she’s never full, and seems a bit slower on walks. It’s tempting to blame it on old age — and many owners do. But this combination of signs points toward something specific: a hormone imbalance called Cushing’s disease, or hyperadrenocorticism.
The honest answer is that Cushing’s symptoms overlap heavily with normal aging, which is why the condition often goes unrecognized for months. This article breaks down the classic signs, explains why they happen, and describes how veterinarians confirm the diagnosis — so you know what to watch for and when to bring your dog in for testing.
What Exactly Is Cushing’s Disease in Dogs?
Cushing’s disease (hyperadrenocorticism) is a chronic overproduction of the stress hormone cortisol. According to peer-reviewed research, it’s caused by a tumor in the pituitary gland (about 80–85% of cases) or the adrenal gland. A third form, iatrogenic Cushing’s, results from long-term use of corticosteroid medications.
Cortisol affects nearly every system in the body. When levels stay high for months, the normal regulatory processes get overwhelmed. The result is a relatively common hormone imbalance in dogs — particularly in small breeds that are middle aged or older.
Pituitary vs. Adrenal Cushing’s
About 85% of spontaneous cases are pituitary-dependent (called Cushing’s disease specifically). The remaining 15% are adrenal tumors. Both produce the same symptoms, and the diagnostic tests your vet uses help tell them apart.
Why These Symptoms Are Easy to Miss
Many owners chalk up the signs to “just getting old.” Increased thirst and urination can be blamed on warmer weather. A bigger appetite might seem like a good thing. Lethargy is often written off as slowing down. But when these occur together, they form a pattern that’s worth investigating.
- Increased thirst and urination (polydipsia/polyuria): High cortisol interferes with the kidney’s ability to concentrate urine, so your dog drinks more and needs more bathroom breaks.
- Increased appetite (polyphagia): Cortisol stimulates hunger centers in the brain, leading to a voracious appetite that’s hard to satisfy.
- Pot-bellied appearance: Cortisol weakens abdominal muscles and redistributes fat, giving the belly a sagging, rounded look.
- Hair loss and thin skin: Chronic cortisol suppresses hair follicle activity, causing symmetrical hair loss on the trunk and skin that bruises easily.
- Excessive panting and reduced activity: Cortisol affects the respiratory center and muscle tissue, leading to panting even at rest and general lethargy often mistaken for aging.
The key is that these signs don’t appear in isolation. A dog with Cushing’s typically shows several of them together, which raises the suspicion much higher than any single symptom alone.
The Most Common Cushing Disease Symptoms Dogs Show
If you’re wondering whether your dog’s changes match Cushing’s, here’s the core symptom set described by the FDA’s increased thirst urination panting update, Cornell Veterinary School, and the University of Illinois. The classic four: polydipsia, polyuria, polyphagia, and a pot belly.
Beyond those, look for reduced activity, excessive panting, hair loss on the trunk (not the legs or head), thin or fragile skin that’s slow to heal, and recurring skin infections. Some dogs also develop a “poor doer” coat — dull, dry, and easily shed.
| Symptom | What It Looks Like | Why It Happens |
|---|---|---|
| Increased thirst | Drinking bowl empty multiple times a day | Cortisol dilutes urine, triggering thirst |
| Increased urination | Accidents indoors, waking at night | Kidneys can’t concentrate urine properly |
| Increased appetite | Begging constantly, eating objects | Cortisol overstimulates hunger centers |
| Pot belly | Sagging, round abdomen | Muscle weakness and fat redistribution |
| Hair loss / thin skin | Symmetrical baldness on trunk | Cortisol suppresses hair follicles |
| Excessive panting | Panting even when cool and rested | Cortisol affects respiratory control |
| Lethargy | Less playful, sleeping more | Muscle breakdown and fatigue |
These symptoms develop gradually. You might notice one or two first, then more over weeks or months. That’s why keeping a simple log of changes can help your veterinarian piece together the pattern.
How Veterinarians Diagnose Cushing’s Disease
Diagnosis starts with recognizing the clinical signs listed above. Your vet will then recommend one of several hormone tests. The low-dose dexamethasone suppression test (LDDST) is the AAHA-preferred screening tool — it measures baseline cortisol, then checks the response to a low dexamethasone injection over eight hours.
The ACTH stimulation test is another option; it measures how the adrenal glands respond to synthetic ACTH. A urine cortisol-to-creatinine ratio can also be used as an initial screening test. These tests are fairly sensitive and confirm the diagnosis in most cases, though false positives are possible, so clinical signs are weighed alongside test results.
| Test | What It Measures | When It’s Used |
|---|---|---|
| LDDST | Cortisol suppression after low-dose dexamethasone | Preferred first-line screening |
| ACTH stimulation test | Adrenal response to synthetic ACTH | Good for iatrogenic Cushing’s and monitoring treatment |
| Urine cortisol:creatinine ratio | Cortisol in urine relative to creatinine | Helpful as a starting screening test |
Your vet will interpret these results in light of your dog’s symptoms. If the LDDST is positive and symptoms fit, treatment is often started. Additional imaging like abdominal ultrasound can help distinguish pituitary from adrenal tumors.
Why Small Breed Dogs Are at Higher Risk
Cushing’s disease doesn’t strike all breeds equally. According to Texas A&M AgriLife, it primarily occurs in small breed dogs middle aged and older. Breeds like poodles, dachshunds, terriers, beagles, and bichon frises are overrepresented. The average age at diagnosis is around 10 to 12 years.
The reason for the breed predisposition isn’t fully understood, but it may involve genetic factors affecting the pituitary or adrenal glands. Large and giant breeds can also develop Cushing’s, but they account for a smaller percentage of cases. If you own a small breed dog over 8 years old, it’s worth keeping the symptom list in mind during regular checkups.
The Bottom Line
Cushing’s disease in dogs is a treatable condition, but catching it early requires knowing what to look for. The core signs — increased thirst and urination, increased appetite, pot belly, hair loss, lethargy, and panting — form a recognizable pattern that’s different from normal aging. If you spot several of these together, it’s worth discussing with your veterinarian.
Your veterinarian can run the appropriate tests, interpret the results, and start treatment plans like trilostane or mitotane if needed. Every dog is different, so what works for another pup may not be right for yours — that’s why a vet’s guidance is essential for managing this condition safely.
References & Sources
- FDA. “Treating Cushings Disease Dogs” Signs of Cushing’s disease include increased thirst, increased urination, increased appetite, reduced activity, excessive panting, and thin or fragile skin.
- Texas A&M AgriLife. “Cushings Disease Can Be a Real Nightmare” Cushing’s disease primarily occurs in small breed dogs that are middle aged and older.